Launchable grenades are used by military and law enforcement organizations for a number of purposes including, target screening, obscuration, concealment, target marking, crowd control, decontamination, and the like. During military field operations, for example, a unit may be targeted visually or detected by devices that rely on ultraviolet, infrared, millimeter or other electromagnetic radiation. Often the most practical and effective countermeasure involves launching one or more aerosol grenades to set up an aerosol cloud in an effort to confuse such targeting and detection systems. Launchable grenades are also increasingly used for dispensing non-lethal payloads including aerosol irritants, non-penetrating projectiles, pyrotechnic “flash-bang” devices, and the like.
Grenade payloads can include phosphorus, titanium dioxide, and other smoke producing and incendiary materials. Other fill materials include particulates that are designed to disrupt or interfere with electronic detection and guidance systems. For example, aerosols made from carbon fiber particles may be released to block targeting that relies on radar or millimeter wavelength sensors. Brass flakes may be used to interfere with infrared tracking and target acquisition devices. Aerosols such as tear gas or pepper mace are dispersed in crowd control and riot situations. Still other payloads may include aerosol disinfectants, decontaminants, pesticides, fire-retardants, as well as non-penetrating projectiles, including rubber “sting” balls, bean bags, sock rounds and other blunt trauma devices.
Currently fielded launchable grenades include the M81 Screening Grenade, M82 Screening Grenade and M90 pyrotechnic smoke dispenser, the M98 Distraction Grenade, M99 Blunt Trauma Grenade and L96A1 and L97A1 non-lethal grenades. Compatible launch platforms include the M7 Light Vehicle Obscuration Smoke System (LVOSS) and the M6 Countermeasure Discharger (CD). The M7 LVOSS is a 4 tube 66 mm grenade launcher designed to be mounted on light vehicles such as the high mobility multipurpose wheeled vehicle or Humvee and is made from lightweight materials. The M6 CD is a 4-tube 66 mm grenade launcher of heavier construction designed for mounting on armored vehicles.
The conventional 66 mm grenade is housed in a frangible cylindrical body and contains an elongate payload section that includes a compacted annular payload that surrounds a high explosive burster assembly at the center. A propulsion section is positioned beneath the payload section and includes an electric match, a lift charge and a pyrotechnic delay fuze.
When the launch operator activates a firing switch, the conventional 66 mm grenade launcher will deliver a 24 volt direct current signal to contacts located in the base of each grenade. Grenades in the same launcher are wired in parallel so that they will fire at the same time. The 24 volt signal causes the electric match to ignite the lift charge, propelling the grenade from the discharger tube of the launcher. The pyrotechnic fuze is ignited by the burning lift charge and, after a delay, nominally of about 1.7 seconds, the fuze detonates the high explosive burster assembly which ruptures the frangible housing and disseminates the payload.
Although the high explosive burster works well at rapidly disseminating the grenade payload, fragmentation of the housing can pose a hazard to personnel in the vicinity of the blast. Non-explosive payload disseminating mechanisms have been developed to reduce fragmentation hazards, as described in U.S. Pat. No. 6,047,644, to Malecki, et al., granted Apr. 11, 2000 (“'644 patent”), and U.S. Pat. No. 6,412,416 to Rouse, et al., granted Jul. 2, 2002 (“'416 patent”), both of which are incorporated herein by reference as if fully set forth.
Developments such as those described in the '644 and '416 patents have expanded the utility of conventional 66 mm grenades and similar devices, however, a number of problems remain. The conventional 66 mm grenade is not highly accurate given today's requirements, frequently takes too long to disseminate the payload, and has a range that is inadequate for many applications. A number of factors contribute to these performance problems. Although the nominal time of flight to a distance of 30 meters is 1.7 seconds, the time delay of the pyrotechnic fuze of the conventional grenade can vary by as much as 0.4 second, resulting in device detonation anywhere from approximately 22 to 38 meters. Projectile instability causes the device to tumble in flight and the blunt nose shape produces drag, adding to the performance problems and targeting uncertainty of the 66 mm grenade.
Differences in launch platform characteristics further degrade performance and targeting accuracy. These differences can arise from a number of factors, including the fielding of discharger tubes in several different lengths, variability in discharger tube bore diameter caused by temperature changes, repeated firings, or other wear and tear, and the presence of non-uniform drain holes in the base of the discharger tubes which dissipate propulsion energy and vary in size with temperature. While the problems of poor range and launch velocity might be solved by simply increasing the size of the lift charge, structural limitations of the discharger tubes of some launch platforms, such as the lightweight M-7 LVOSS, prevent increasing the size of the lift charge. In addition, increasing the size of the lift charge would likely exacerbate targeting accuracy problems.
Such drawbacks, and others, limit the effectiveness of the conventional 66 mm grenade and other similar munitions in a growing number of applications where greater accuracy, shorter time to target and/or greater range are needed to disseminate a grenade payload with greater effectiveness and reduced risk to non-combatants or friendly forces. Any improvements should also be backwards compatible with existing systems, to the extent practicable. These and other problems are solved, at least in part, by embodiments of grenade systems in accordance with the present invention.